Oil burning furnace



g- 1, 1939- I H. s. WOODRUFF 2,163,134

OIL BURNING FURNACE Filed Dec. 15, 1935 4 Sheets-Sheet 1 INVENTOR. fl /m fll awiarz,

Aug. 1, 1939.

H. s. WQODRUFF OIL BURNING FURNACE 4 sums-sheet 5 Filed Dec, 13, 1935 0 a I Q M ATTORNEY. f

Aug. 1, 1939. H. s. WOODRUFF OIL BURNING FURNACE 4 Sheets-Sheet 4 Filed Dec. 13, 1935 ATTORNEY.

Patented Aug. 1, 1939 v 2,168,184

UNITED STATES PATENT OFFICE OIL BURNING FURNACE Henry S. Woodruff, Larchmont, N. Y.

Application December 13, 1935, Serial No. 54,156

3 Claims. (01. 122-.-156) This invention is directed to furnaces, more furnace made in accordance with the present particularly to small size furnaces including invention, some parts being shown in elevation mechanism for burning oil as the fuel and infor clearness;

tended for use for household and similar pur- Fig. 2 is a fragmentary, front elevational view poses, of the burner unit showing particularly the 5 This invention i dir cted to a, ombined furmeans for locking the unit in place for operation;

nace and oil burning unit wherein all of the Fig. 3 is a vertical, Cross-Sectional View Of the mechanism necessary for the operation is conur a tak n t ri an s to the ction of tained in a single shell. Furnaces of this type some parts being Shown in elevation for have been used heretofore and have functioned a ss; 10 with reasonable efficiency. However, the con- 4 is a t p w p y in Section and p y struction of such furnaces has in general been in pla Sa d u ace; complicated and has required expensive cbn- 5 is a front w f a ur e S i in struction by reason of considerable hand labor slightly medlfied form eonstruetion; nd. p

and close fitting of numerous parts of irregular" Fig. 6 is a fragmentary side view of the furnace 15 design and shape. Many of the parts have been Shown in some parts being ow in inaccessible and the cost of repairs has, theresection. V fore, been unnecessarily high, There is provided a substantially cylindrical The present invention is intended and adapted Vertical she l I, Ope at the bottom and having to overcome the disadvantages and difficulties of a m shaped p A y n i l V r ly 20 prior furnaces of this type, it being among the placed outer shell 3 surrounds the inner shell, objects of this invention to provide a furnace t s d s ls being n ri w t sp t to structure which is simple and compact, which each other, as m rl shown in F may be readily made in quantity producti circular horizontally placed top and bottom boiler which .does not require special parts or high1 sheets 4 and 5 are welded to said sheets. A stay 25 skilled labor, in which the various elements are rod 6 is welded to dome 2 and Sheet 4 t0 Strengthreadily accessible for replacement or repair and en the structure. Fire brick, or similar heat inwhich is efficient in the utilization of fuel. sulation, 1 lines the lower Portion of S ell l and In practicing my invention, I provide a furnace st p n a ledge 3 constituting an e s o of sheet metal usually of steel and consisting of sheet 5. A series of vertically placed oval or 30 essentially of substantially flat, horizontal top flattened flues 9 is also welded intosheets 4 and 5. and bottom boiler sheets between which are Said flues are placed in the wider portion of the welded inner and outer shells of substantially space between the two shells, as shown in Fig. 4, circular, cross-section, and offset with respect to and they are substantially in parallel relation to each other. In the widest portion of the space obtain a maximum amount of heat transfer sur- 35 between said sheets there are welded a series of faces in the minimum of space available. The flat flues designed to facilitate the extraction of lower ends ill of said flues communicate with the heat from the gases. The burner unit is below combustion chamber of the furnace and the upthe inner shell and the mixture of air and oil er ends ll lead into a casing i2, the open end -10 u r m us pa s s, p d y w t a rotatl3 of which leads to a chimney. A plate 14 4o ing motion into the inner shell where combustion bolted to Said Casing provides ready access to takes place and the hot gases of combustion pass the fines for cleaning purposes to the dome of said shell, then outwardly and At the bottom f t furnace is an opening downwardly along the sides thereof and then 1nto mm which is fitted a pipe '5 for return or supply 2 1 3; i ig ggg through the water to the furnace. In the sheet 4 is an open- 45 Various other novel and important features of mg 1S g i n for Steam my invention are described and claimed herein to t to t e ,eatmg y An and such features will be apparent from the opening I8 in said sheet 4 1s fitted with a presdescription given below, sure release or safety valve I9. A float 20 oper- 50 o embodiment of my invention is Shown in ates a switch to cut off the burner if the water the accompanying drawings constituting a part level gets A gauge ss 2| o usual hereof, and in which like reference characters construction is provided at the frontof the furindicate like parts. nace and a pressure gauge 22 is inserted at a -Fjg. 1 is a vertical, cross-sectional view of a point just above the water gauge. A cap or 55 cover 23 fits over the top of the furnace enclosing the casing l2.

A rectangular member 24 is welded into the shells and 3 and provides a rectangular opening which is protected by an insulating member 25 having a central opening. A sight glass 26 is fitted opposite said opening and a disk or other protective member 21 is interposed between the combustion chamber and said glass 26. An operating lever 28'secured to the upper end of disk 21 is provided with an operating handle 29 on the outside of the furnace. A cover 38, U-shaped in cross-section, is hinged at 3| to the furnace jacket and extends from substantially the top thereof to the top of the lower band or skirt and serves as a means for protectingthe gauge 22, glass 2| and sight 26 from dust or injury. Said cover is provided with a glass 32 to enable the inspection of gauge 22 and glass 2| without opening said cover.

Insulation 33 of the cellular type is placed on sheet 4 and similar insulation 34 is placed around shell 3 and a metal jacket 35 surrounds the same and holds it in place. The furnace is supported on a plurality of legs 36 which are suitably secured to sheet 5. The space below sheet 5 is surrounded by a skirt 31 secured to the furnace in such a manner as to be readily removable at least in part. For this purpose, the sheet is usually made in two parts 31 and 31'.

Secured to the bottom of the furnace is a pan 38 having in the bottom thereof heat insulating material 39 and having an opening 48 therein in line with the axis of shell I. At the rear of the pan is secured an eye 4 I. At the opposite or front end of the pan is a boss 42 having pivoted therein a downwardly extending lever 43. The lower end of the lever is provided with a pin 44 on which is pivoted forked member 45 having a fiat extension or handle 46. At an intermediate portion of lever 44 is a pair of pins: 41 as most clearly shown in Fig. 2.

To the pan is removably secured an oil burner unit designated generally as 48. It comprises a support or base consisting of a flat member 49 having an opening to which is secured a fiat cylindrical upwardly extending member 58 terminating in a member 5| having diagonal waves along the inner periphery thereof. A hook 52 at the rear of the plate 49 is adapted to fit into the eye 4|. At the opposite end of plate 49 is a pair of hook members 53 adapted to fit over pins 41.

Secured to plate 49 is a pan-shaped member 54 on the lower side of which is secured motor 55 to which in turn is secured oil pump 56 connected with oil feed pipe 51 which terminates in burner 58, having atomizing nozzle 59 extending into cylinder 58. The shaft of motor 55 extends through an opening in pan 54 and there is secured thereto a blower 68 provided with a perforated cover 6|. Also secured to pan 54 and below the same, is ignition unit 62, the high tension terminals 63 of which are connected to spark discharge members or plugs 64 terminating in proximity to nozzle 59. To plate 49 are attached control unit 65 for the usual relays and other controls for the burner mechanism. A source of power or cable 66 terminates in a plug 61 fitting into a socket in control unit 65, said plug having a flat lateral extension 68 adapted to overlie handle 46 when the burner unit 48 is in position.

A fire detector 69 extends through the wall of pan 38 to the flue and has a cable 18 extending from the outside of pan 38 to socket 1| of control unit 65. The cord 18 is so fixed or is of such length that the plug attached thereto can reach socket 1| and be inserted therein only when burner unit 48 is in its proper locked position. Formed on motor 55 is a boss 12 carrying a pair of casters 13 on which the burner unit 48 is adapted to be rolled.

At a point 14 in a space between shells and 3 at a point intermediate to the fiues 9 and the narrowed portion of the space between said shells, is inserted a unit for the heating of domestic hot water. In sheet 4 is a boss 15 into which is fitted a header 16 into which is inserted a series of pipes 11 usually of copper, bronze, brass, or the like. Any number of such pipes may be utilized, and I have found that two rows of four pipes each form a unit which is usually adequate and which will readily fit into the available space. Said pipes have one or more offset portions 18 to allow for unequal expansion of the furnace and said pipes. The lower end of said pipes fit into a header 19 one side 88 of which is rounded as shown in Fig. 3. An opening 8| opposite header 19 allows the introduction of pipe 82 and a nut 83 is fitted thereover to make a water-tight joint, as is usual. The header 16 is secured in place by flange member 84 which is bolted onto sheet 4. A pipe 85 is fitted thereto and pipes 82 and 85 are fitted to the hot water tank or the like.

In order to provide a safety device to prevent accidental rupture of the boiler under unusual conditions, there is provided an opening 86 in shell 3 into which is fitted a plug 81 having secured therein a disk 88 of metal or other material. The strength of said disk is substantially lower than the calculated strength of the boiler shell, but is greater in strength than the maximum pressure for which the boiler is designed. Therefore, under unusual conditions of pressure, disk 88 will blow out and thus prevent explosions. A new disk or a new plug can be placed into position very readily, particularly if the arrangement is placed underneath cover 38. Such an arrangement is desirable when using boiler shells of extreme thinness where fire regulations may require safety devices.

In the operation of the furnace, unit 48 is rolled into place on casters 13 and hook 52 is inserted in eye 4 Handle 56 is manipulated so that pins 41 fit into hooks 53 and a downward movement of the handle will raise unit 48 into position, and when handle 56 touches unit 65 the burner unit 48 is locked into proper position. By this movement the shell 58 is caused to rise into opening 48. When the unit 48 is properly locked in place, pins 49 are in such a position that the axis thereof is to the left of pin 44, as shown in Fig. 1. Plug 61 is fitted into its socket and extension 68 will lie over handle 46. If the handle is not in proper position, the socket 61 will not fit sufiiciently into its socket to make proper contact. The plug of cable 18 is fitted into socket 1| and this can be done only when unit 48 is in proper position.

Upon the starting of the burner, oil and air are mixed and they flow upwardly with a swirling motion approximately as shown by the arrows in Fig. 1, in a fan-shape and spread out until the flame almost touches insulation 1. The gases of combustion hit the dome 2 and are deflected outwardly and downwardly along the sides of shell I and insulation 1, then upwardly through flues 9 and out through casing l2 and into the chimney. The gases take the form shown by the arrows in Figure 1, having a constricted area at the lower end. The gases of combustion passing downwardly along the sides of shell I are substantially in contact with the burning mixture of fuel and air. By reason thereof and also by reason of the low pressure at the base of the flame, some of the combustion gases will become entrained in the burning mixture. tion of such gases varies with a number of factors and is controllable. This is of considerable importance in that the presence of the proper amount of combustion gases in the flame tends .to make the flame less noisy. An inspection of the boiler pressure and the water level is made through window 32 and inspection of the combustion chamber may be obtained by opening cover 30 and rotating handle 29 a distance of about 45, which allows a view of the combustion chamber through sight 26.

In the modification shown in Figs. and 6, the primary control box is located in a diiferent and more readily accessible position and it is combined with the flame detector. The flame detector 69 is situated in shell I near the dome 2 thereof and passes through the outer shell 3 into control box 65', which is located above the sight opening 26 and under the door 3|]. Limit control box 89 is placed in proximity to the limit controls, such as the water level control, aquastat, etc., and also under door 30. A cable 90 connects the same to box 65' and cable 66' extends downwardly under the door 30 and skirt 3'! and is just long enough to fit into socket 9| on bracket 92 fixed on plate 49, when the burner unit is in its proper position. A cable 93 is adapted to energize motor 55.

Efiicient performance of a small oil burning heating unit such as used for domestic heating, depends on two factors. First, complete and eflicient burning of the oil with the minimum amount of excess air, and second, the efiicient transfer of heat from the flame and burned gases or products of combustion by radiation and convection.

The first factor is by far the most important, since in oil heating units of the size under discussion from 70% to 80% of the total heat of combustion should be transferred to the water through the walls of the combustion chamber, depending on the rate or amount per hour of oil burned. The percentage decreases as the rate and size of boiler increase. This is partially due to the relations of volumes to areas in objects of similar shape but varying in size. As the size of the combustion chamber is reduced, the unit area becomes larger in proportion to unit volume and, since the rate and amount of heat transferred is governed by unit area, as well as relative temperature, the smaller units transfer a larger percentage of the total heat in the combustion chamber.

It will be seen from this that the proportions, volume and temperature of the combustion chamber are of paramount importance and all bear a fixed relation to the rate of oil burned.

As the proportion of heat transferred in the secondary surface or flue passes increases, the area. of secondary surface necessary goes up rapidly, since the transfer is almost entirely by convection with practically no radiation and the temperature of the gases drops rapidly as they enter the flues. This results in a rapidly decreasing rate of transfer per unit of area.

The use of true cylinders for eombustiolnchamber and outer shell of a domestic heating boiler is very desirable, since it avoids the expensive construction involved in staying flat surfaces.

The propor- Another very desirable feature of domestic heating boilers of cylindrical, welded steel,'one piece construction is that the largest diameter shall be something lessthan 30" so that the boiler may be moved through doorways of minimum standard width.

The design of this boiler combines a 1% gal. of oil or its equivalent in other fuels per hour capacity and the related combustion chamber dimensions, with the low cost cylindrical construction and an outside diameter of less than thirty inches. The diameter of the inner shell should be not less. than about 19" and its length 30" to 31", When burning its rated capacity of oil, the efliciency of heat transfer to the water is not less than 78% and may be as high as 80% or 81%. This is believed torepresent the best; com;- bination of features, namely, maximum capacity with minimum cost.

Although I have described my invention setting forth a single specific embodiment thereof, it will be apparent that my invention is not limited tothe details described herein and that wide variations in construction may be made within the scope of my invention. For example, the invention is applicable not only to a steam, heating system, but also to hot water and vapor systems. It is also applicable togas fired furnaces, as well as those using powdered coal. Various changes in the materials used, the details of construction, the form and arrangement of various parts, etc., may be made as will be apparent tothe individual skilled in the art. These and other changes may be made in my invention which is to be broadly construed and is to be limited only by the scope of the claims appended hereto.

What I claim is- 1. A furnace comprising an inner vertically extending elongated shell closed at the top and constituting a combustion chamber, an enclosing vertically extending outer shell, said shells being spaced from each other to form a water compartment between them, a flue, the lower end of which is in communication with the lower end of said inner shell, said flue extending vertically of said water compartment and through the upper end thereof adjacent the upper end of said outer shell, a pressure type burner soconstructed and arranged as to project a column of flame upwardly into said elongated shell, said flame being immediately surrounded by said inner shell thereby exposing the inner shell directly to the radiant energy from said flame, the closed top of said inner shell effecting deflection of the combustion products into contact with the inner surface of the inner shell and their passage downwardly along the same and into said flue, and the upwardly projected flame effecting entrainment of some of the downwardly moving combustion products into the flame.

2. A furnace comprising in combination an inner vertically extending elongated shell closed at its upper end and constituting a combustion chamber, an enclosing vertically extending outer shell out of communication with the inner shell, said shells being spaced from each other in eccentric relation to provide a water compartment between them, flues extending vertically of said water compartment from top to bottom thereof, the lower ends of said flues being in direct communication with the interior of said inner shell, the upper ends of said flues projecting through the upper end of the water compartment, a pressure type burner so constructed and arranged as to project a column of flame upwardly into said 15 elongated shell, said flame being immediately surrounded by the inner shell, the closed upper end of the inner shell effecting deflection of combustion products into contact with the inner surface of the inner shell and their passage downwardly along the same and into said flues and the upwardly projected flame efiecting entrainment of some of the downwardly moving combustion products into the flame.

3. A furnace comprising an inner vertically extending elongated shell closed at its upper end and constituting a combustion chamber, an enclosing vertically extending outer shell, said shells being spaced from each other to form a Water compartment between them, a flue, the lower end of which is in communication with the lower end of said inner shell, said flue extending vertically of said water compartment and through the upper end thereof adjacent the upper end of said outer shell, a pressure type burner disposed concentrically with respect to said inner shell and so constructed and arranged as to project a column of flame upwardly into said elongated shell, said flame being immediately surrounded by the inner shell, the closed upper end of the inner shell deflecting combustion products into contact with the inner surface of the inner shell and their passage downwardly along the same and into said flue, and the upwardly projected flame effecting entrainment of some of the downwardly moving combustion products into the flame.

HENRY S. WOODRUFF.- 

